This invention relates to a molded product for colored food which undergoes discoloration with difficulty even when contacted with a colored food such as vegetables, fruits, etc.
Polyolefins are inexpensive and also have excellent molding characteristics, and hence have been widely used as food vessels or implements.
However, molded products made of polyolefins will undergo discoloration through contact with colored foods, for example, vegetables such as spinach, white rape, etc. and fruits. For solving this, for example, in Japanese Provisional Patent Publications No. 125450/1978, No. 36150/1984 and No. 113632/1986, polypropylenes formulated with additives such as sulfur type stabilizers, phenol type stabilizers, paraoxybenzoic acid or higher fatty acid alcohols, etc. have been known, but the effect is not satisfactory and further improvement has been desired.
Generally speaking, concerning discoloration of the molded product with a colored food of fresh vegetables and fruits and processed products thereof, its cause may include coloration with the dye contained in them, coloration through spoilage of vegetables, discoloration with the colorant for food, and further discoloration through mutual interaction between various additives and the dye, etc., but has not been clarified yet.
Also, polyolefin is generally susceptible to thermal oxidation deterioration due to its chemical structure, and cannot stand the heat during processing and use. For this reason, a product which can stand practical application can be obtained usually by formulation of an antioxidant for inhibition of thermal oxidation deterioration, but there ensues the problem that coloration from the colored food becomes more marked with the antioxidant. Further, inhibition of odor is another problem to be solved.